Performance Enhancement of Upwind Dynamic Soaring by Thrust Augmentation

Dynamic soaring is a flight mode by which an energy gain from the wind can be achieved so that flying without cost is possible. The amount of gainable energy depends on the shear wind strength and the flight direction relative to the wind. This issue is addressed for upwind dynamic soaring with regard to the necessity of enhancing the flight performance using thrust from an engine. For dealing with that problem, flight mechanics and shear wind models for upwind dynamic soaring are developed and an optimization method is used for constructing solutions. It is shown what are effects that headwinds exert on dynamic soaring. Shear wind scenarios are identified where upwind dynamic soaring requires an augmentation by engine thrust in order to make progress against the wind. The minimum of the energy cost required for the thrust augmentation is determined. Furthermore, it is found that there are shear wind scenarios where a thrust augmentation is not required for upwind dynamic soaring. This can hold for moderate wind speed levels.